Odorization of Gas (16.11)

Odorization of Gas (16.11)

Description of Key Area

Odorization of gas is
considered under Subpart L (Operations) of 49 CFR 192. The Code states that a
combustible gas in a distribution line must contain a natural odorant or be
odorized so that at a concentration in air of one-fifth of the lower explosive
limit, the gas is readily detectable by a person with a normal sense of smell.

Discussion of Criticality

Odorants compatible with
hydrogen have not yet been found. The sulfur found in traditional natural gas
odorants can, even at very low concentrations, damage fuel cells. It is also
impractical to implement odorant removal equipment at each point of use.

Discussion of Progress

A successful, efficient,
and cost effective method of hydrogen odorization has not yet been identified. Although
there are odorants compatible with hydrogen, it is difficult to envision
odorizing of hydrogen with sulfur-containing compounds. The Japanese Auto
Research Institute (JARI) is working on a non-sulfur based odorant for
hydrogen. Other organizations are also actively conducting research on
different classes of odorants to make hydrogen leaks detectable by humans. ASME
B31.12 will not address this topic.

Recommendations

Current research for
hydrogen odorants must address the odorants potential impact on transportation
technologies and on end use technologies. Once research is completed, standards
for hydrogen odorants must be established and incorporated by reference into
the federal code. It may be necessary to re-examine odorant detection limits
that are incorporated into 49 CFR 192.